An eFuse is a simple circuit element that has one of two different states: blown or unblown. As is generally known in the art, data may be written to eFuses by selectively blowing eFuses in an array of eFuses where the blown and unblown eFuses correspond to “1”s and “0”s.
For example, many integrated circuit chips use arrays of eFuses to store redundancy information and records of manufacturing, such as wafer identification. Specific chip designs also use arrays of eFuses to store proprietary software code, passwords, and classified information.
However, data in an array of eFuses is not secure and can be accessed through at least two methods. First, the state of an eFuse can be accessed by monitoring the current that is conducted through that eFuse. While there are known methods of making it more difficult to measure the current across an eFuse, these methods can be overcome. Second, the state of an eFuse can be accessed through optical, thermal, or photonic inspection of the eFuse. Again, while there are known methods of making this inspection more difficult, these methods can be overcome.
Accordingly, there exists a need in the art to provide more security to eFuse arrays and overcome the deficiencies and limitations described hereinabove.